Insofar as oxygenators are concerned, three main types are generally known. The oldest is probably the type where a blood film is formed in direct contact with an atmosphere containing oxygen. In the second type, the oxygen is made instead to diffuse through a semipermeable membrane from an atmosphere containing oxygen on one side of the membrane to the blood on the other side. The third type, to which the apparatus in accordance with the present invention belongs, is generally known as bubble oxygenator. In this type, gas bubbles containing oxygen are introduced directly into the blood so as to directly act on the same. After the desired action, the excess gas is removed from the blood together with any substances transferred from the blood to the gas.
Examples of constructions of bubble oxygenators are shown, for example, in U.S. Pat. Nos. 3,175,555; 2,934,066; 3,545,937; 4,037,622; 3,468,831; 3,488,158; 3,615,238; 4,058,369; 3,578,411; 3,291,568; 4,033,724; 3,827,860; 3,853,479; 4,067,696; 4,065,254; 4,138,464; 4,138,288.
More particularly, the present invention is an improvement of the apparatus shown and described in international patent application No. PCT/SE80/00096, filed Apr. 3, 1980 and published under No. WO 81/02836 Oct. 15, 1981.